Walled Cyclones (WC) are mechanical apparatus utilized for the collection of aerosol particles for detection of trace levels of certain biological, explosive, chemical and nuclear materials. The principle of operation is to separate particulates present in the air based on size by taking advantage of the trajectory and flow dynamics of submicron particles as compared to macroscopic particles as the particles enter a rotational vortex in a pipe. The larger particles are acted on by inertial forces that push and separate the larger particulate to the inner wall of the cyclone while the smaller air gas molecules will be exhausted through the center of the pipe, exhausted out via a blower, fan or other air moving device. The inner surface of the cyclone is wetted, coated or consists of a material conducive to capturing particulates. Its surface is conditioned for the purpose of transporting or flushing the particulates into concentrated samples to be evaluated by biological, chemical, explosive or nuclear sensors, detectors, and identification apparatus.
FIG. 1 shows the basic architecture of a collection mechanism. The main body 102 is a pipe. The body is a molded or machined part that forms the interior and exterior surfaces of the cyclone. Within body 102 is a vortex finder 104. The vortex finder is a cone shaped protrusion at the bottom of inlet tube 106 that enhances the creation of a vortex in the cyclone body when air is flowing. An inlet tube 106 allows for inlet of air. The inlet tube provides a contoured interior surface that directs air flow from the entrance located on the upper portion into the cyclone body. An opening in body 102 allows the air to flow into the collection tube of body 102 through the opening. A wetting port 108 inserts a liquid that wets the air impaction region or cyclone body below the air inlet within body wall 102. In the wetting port a liquid may be injected into the cyclone for formation of a wetted surface along the cyclone wall for particulate collection. Air flows in the interior of the body 102 to an air outlet 110 where it is exhausted. The air outlet is interfaced to a blower or some other air suction device that generates the negative pressure that induces flow in the cyclone. While the air flows toward the exhaust, particulates flow along the wetted interior surface of body 102 toward a collection port 112. The particulates are collected at the collection port for future transport to sensors, detection devices and identifiers.